FRONTLINE Spray provides an effective flea and tick control for dogs, and puppies. Because of the spray formulation, fipronil, the active ingredient in FRONTLINE Spray, is immediately distributed over your dog’s body and begins to kill fleas shortly after application. This makes FRONTLINE Spray fast acting to control an existing flea or tick problem. Control is also long-lasting, since the fipronil remains in the natural oils lying just beneath the coat of your dog. Your dog can be bathed, can splash in puddles, and even swim without losing protection against fleas and ticks for a month.